LAUSR

ABSTRACT In this paper, radiation characteristics of an isosceles 45°–45°–90° triangular microstrip antenna (TMA) are presented using simple extension of cavity model considering field variation in all dimensions for the first time along with physical explanation. Eigenfunctions, eigenvalues, input impedance, far-field radiation patterns, etc. are discussed. Approximate expression is given here to predict the resonant frequency with accuracy better than 1%. Theoretical results are verified with experimental data to show the accuracy of our theory. The study of 45°–45°–90° TMA is important because (1) the area occupied by the antenna is just half of that compared to a square patch antenna for a given resonant frequency, (2) mode suppression (including fundamental mode) of the antenna is quite easy compared to other conventional shaped patch antennas, (3) all modes of the antenna are dual polarized, and (4) four modes out of first five modes of the antenna produce a peak in the broadside direction.